Friends, The basics for the dam-dial is a shadow tangent to an hour line.
More about these basics may be read in: Compendium, Nass, vol. 12, nr. 4, December 2005, Alessandro Gunella, Italy, A sphere as a gnomon...... Compendium, Nass, vol. 13, nr. 1, March 2006, letters....., Note by Rolf Wieland, Germany, Spherical gnomon. Instead of a sphere here a horizontal disk, the edge of the ballustrade, is used as shadow caster. Best wishes, Fer. Fer J. de Vries De Zonnewijzerkring http://www.de-zonnewijzerkring.nl Molens http://www.collsemolen.dse.nl Eindhoven, Netherlands lat. 51:30 N long. 5:30 E ----- Original Message ----- From: robic.joel To: Roger Bailey ; Bill Gottesman ; Willy Leenders Cc: Sundial List Sent: Friday, June 19, 2009 7:47 AM Subject: Re: Translations Hello Roger and all, You are right, this silo dial shadow reminds the dam dial shadow, and is very impressive too. However, the time reading is not the same, With the dam principle, you use the shadow envelop, Gérard Baillet made a vertical cylinder dial as the silo, and translucent to read the time on the external side, see the lines, it is 13 O'clock (1:00 P.M.), the 13 hour line tangents the shadow: This one was designed for my location. Joël 48°01'25'' N, 1°45'40" O ---> http://www.cadrans-solaires.fr/ ----- Original Message ----- From: Roger Bailey To: Bill Gottesman ; Willy Leenders Cc: Sundial List Sent: Friday, June 19, 2009 2:43 AM Subject: Re: Translations This dam dial reminded me of a similar sort of dial in a silo in Louisa VA. See the NASS Registry #594 or go to this direct link to the dial. http://www.louisasundial.com The silo sundial was created in 1985, designed by Dr. Larry Kavanagh and painted by family and friends. I believe it is an altitude dial with the gnomon point being the rim at the point in line with the sun. The gnomon point naturally moves with the azimuth of the sun. The lowest point on the shadow tells the time against the time lines. Regards, Roger Bailey ------------------------------------------------------------------------------ --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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